Transmitting apparatus for train communication systems



7 Feb. 3, 1942. I s 2,272,106

TRANSMITTING APPARATUS FOR TRAIN COMMUNICATION SYSTEMS F'il ed Jan. 13,1941 Madahzor Amplz'fibr llazop 4 A. iz'zzalljzk'ell Inbound YardPatented 3, 1942 -:{TRANSMITTINGAPPARATiiSEOR'TRA N' j aCOMMUNICATIONJSYSTEMS v ramp. Ash, iijiiisviue, iKy',

' 'ApplicationJanuary 13, 19 411; Serial No.

OLE 46. 8) I .My invention relates .to "t ransmittiiigsappae ratustori-train communicationsystems,iand' niore particularly to transmittingapparatus for communication'system's 'for'classification yards; Railwaytrain communication systems :ordi narily use a carriercurrent;For'telep'hone com-L munication ;a carrier of a wpreselected "frequencyis modulated "by the voice 'frequencies and :a selected sideband istransmittedfthenarriir and the other side. band being, ordinarily atleast,

suppressed. 'In' such fa system a calling orsig naling currentequivalent "to a the carrier 'niodulated by a preselected frequencywithinthe voice frequency 'rangeis. employed. In railway cla'ssification"yards such communication 'systerris'are usedior directing; themovements ofshifting lo.- comotives from 'acentralzyard oflice,"and ithas been proposed that the calling or signaling our U i sw ch-ant SlJQQmPg nYL Pa., a corporation fof Pennsylvania Jtion yard orirbetweeniI oflice: and the crews of all'the locomotives withintheclassificationyardg"a; v; x f Ii The above. features; of Emy invention;as well -as 1 tween the operator, atacentral oifice stati niand thescrew of a locomotive operatin ,in either the inbound 'org in 'tlieoutbound yard of acIaSSAflOa the operator; at the central otheradvantages whiohwill become apparent as a the specification ;progresses-, are attained accordapparatus: ihavin in I0 my-=-invention l by jprovidingtransmitting a first j. manually operable sw tchin ,nieans at.one os t on o I w 1 th apparatusto rent be transmitted 'at all timesexcept when.

telephonecommunic'ationis desired to provide a) a cab signal indicationthattchecks "the operative condition of the apparatus; In classificationyards where a humpis use'd,"a fixed wayside sigrial 'of the semaphore'or I'color light type islo-; cated in the vicinity or the vhump "and iscon trolled by the yard conductor to signal to the shifting'Iocomotiv'the "spee'dand movements desired for thecars' that are beingclassi'fiedloy n being pushed over the "hump. Such a fixd'signal may notalways be effective because of the g:-

limitedv visibility under bad weather conditions. Acc'ordingly'a featureof nay-invention is the the; ap aratus s re h of; t a k transmittingapparatus-is;conditioned to produce a d at; n thenp I tionj at 3 whichthe apparatus J is conditioned to a carrier signaling current produ e acar ie telephon c rren and e c of whic curr n s s ied @by h t m n .a ionpn E ri ui 1 uch out :c'i cuit *is, connected ;to*;a j transmittingcircuit extend n a on -astret a a ed rorjc mm nicat n n, ajclassificationx a c twoermom transmitting G n cu ts i may-sheneared-1.0 such ansmi t n circuit ma bex or examp s c d it o h-asthetracks of the in-,

oundsa d a sec d rans itting circ i may be i asscciated withagsecondstretch of track such asjthe tracks"of-"the;outboundyard. When twotransi s pi u tsl"are p o ided, th -butprovision of novel andimprovdtransmitting apparatus for train communication systems-I Another ieatureof my invention is the provision of novel andim'provedtransmitting apparatus 'for train communication systems for 'classification yards. 7 a II i Again, a 'feature or "my invention isthe'p'rovision of apparatus fortrain communication. sys'iterns 'fincorporating novel transmitting{means for supplying a carrier signaling current which -is..coded atdifferentcode rates whereby-"such coded signaling current maybeusedxtoz' govern different'ca'b signal indications.

Another feature of y invention is rtheprovi sion of transmittingapparatus "for' train} comsition of the? putcircui selectivelyconnectedto such-trans- Smitting'fci cuits jby ag manually operableswitchingumeans lra ing; different positions so that the cu nl t cicuitinaywb fi nne e to any *on or-t "all oflthe, transmittingjcircuita yA" codetransmi-tteriisi governed by said one po- 7 first switching meanstog-code at times the carrier 1 signaling current. "Such: codetransmitter is? provided .with f differe'nt contact members twhichzareoperated at"different rates {and e'ach'gsuch code contact member isfincluded in a1p'articula'rv circuit 'p'athzof the output circuit..

A second :manual-l'y' :operablei switching: means having-severaldifierentpositions is provided and byits :positibni determines" whichcircuit' path: of

the'outputcircuit is closed and hencedetermines by its positionfwhichone of the: code contact membersis effective to code the "signalingcurmunication systems for classification yards wherewith a carriersignaling current iscodedat' difierent codes to provide. differentcabfsi'gna'ls ;for the different speeds and movements required forclassifying cars, and which codes; of'th'e signaling current are madetocorrespond .to .thexdife r ferent indications of a fixed signal. Furthermore, telephone communication 'is efifcted bea tiongsysten offaswitching means i would also preferably fgovern I rent-.j Thi'sfsecondaswitching means'includes an additional position at which" the outputcircuit is 'by-pass ed around the contact. members oif'the" icodetransmitter for *s fpplyingf at V time's 5 a noncoded 'sighalingkcurrent. I I

" When the 'apparat' s isusedfo'r, communi n classification yard, the;second h or :the railway and when the fixed signal usually provided fordisplaying a different signal indication for each of the differentspeeds and movements used to classify cars. Under such circumstances thesecond switching means by its position provides a specific code for thecarrier signaling current for each indication of the fixed signal, andhence there is a code for each of'the different speeds and switchingmovements to be used in classifying cars.

A second position contact of the first switching means, which positionconditions the transmitting apparatus for supplying telephone current,completes a circuit path of the output circuit which by-passes thecontact members of a code transmitter and the second switching means andhence for telephone communication the telephone current is delivereddirectly from the transmitting apparatus to the transmitting circuitsaccording to the position of the previously mentioned other or thirdswitching means.

I shall describe one form of apparatus embodying my invention and shallthen point out the novel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form ofapparatus embodying my invention'when used with a train communicationsystem for a'classification yard. Referring to the drawing, thereference character RY designates the inbound or receiving yard of aclassification yard, and which inbound yard is shown as comprising threetracks IT, 2T and 3T. The reference character OY designates theoutboundyard of the classification yard, and this outboundyard is shown as alsocomprising three tracks 4T, ST and GT. Traiiic normally enters theinbound yard RY from a main track (not shown) to the left as viewed inthe drawing. Trafiic leaves the yard RY over a hump track HT andfromthis hump track cars move into the outbound yard OY. In accordance withthe usual practice, cars are collected on the several tracks of theinbound yard and are then pushed over the hump by a shifting locomotive.I The movements of the cars from the hump to the several tracks of theoutbound yard may be governed by car retarders or car riders as desired,the cars being classified in the several tracks of the yard Y accordingto the destination of their lading. Shifting locomotives operating inthe yard RY or in the yard CY and locomotives pushing cars overthe humpare under the direction of a yard master or operator located at acentral ofiice station shown atCF in the drawing.

Although only three tracks are shown for each of the yards RY and OY, itwill be understood that each yard may be provided with additionaltracks, each of which additional tracks would be connected to the humptrack by the customary ladder track. It will also beunderstood that myinvention is not limited to a classification yard or'to a classificationyard using a hump for the classification of'cars, and this oneembodimentof the invention will serve to illustrate the many placeswhere apparatus embodying my invention is useful.

' In'order that the operator located at the central ofiice CF maycommunicate both by cab signaling and by telephone communication withthe crews of the locomotives operating on any track of theyard andthereby direct the movements of such locomotives quicklyand efiiciently,apparatus embodying my invention is provided and which apparatusincludes transmitting apparatus located preferably at the central ofliceCF and transmitting circuits extending throughout the yard.

The transmitting circuits may take different forms and would preferablybe of the type covered by the Letters Patent of the United States No.2,112,364, granted March 29, 1938, to L. O. Grondahl, for Electric trainsignaling systems and wherewith the track rails are included in thetransmitting circuit. In the specific embodiment of my invention twotransmitting circuits are provided, one being associated with the yardRY and the other being associated with the yard OY. The firsttransmitting circuit includes a line wire LI extending from a, pointnear the central oflice station to a point A at the extreme left-handend of the yard RY. At point A, the line wire Ll is connected by a wire4 to at least i one track rail of each of the tracks of the inbound yardRY. From the point A, the circuit extends through the rails of theseveral tracks of yard RY in multiple to the hump track HT and thence toa point adjacent the central oflice CF. The track rails may be bonded bythe usual rail bonds to improve their electrical conductivity, but suchbonds may not be required since the rails are electrically continuousdue to the splice bars and bolts of the rail joints.

The second transmitting circuit includes a line wire LO extending from apoint adjacent the central oflice CF to a point D at the extremeright-hand end of the outbound yard OY. At point D, line wire L0 isconnected by a wire 5 to at least one rail of each of the tracks of theoutbound yard OY. From point D, the second circuit extends through therails of the several tracks of the outbound yard in multiple to the humptrack HT and thence back to office station CF.

Each of these transmitting circuits is intended to cooperate withlocomotive carried receiving apparatus responsive to communicationcurrent of the character here contemplated when such communicationcurrent flows in the rails, energy being preferably transferred from thetrack rails to the locomotive carried apparatus inductively through themedium of an inductor mounted on the locomotive in inductive relation tothe track rails. It will be observedthat each transmitting circuit isnot shunted by the. wheels and axles of a car or locomotive, and therails of each track form a branch path in the transmitting circuit sothat energy will be transferred to the receiving apparatus irrespectiveof the track occupied by the locomotive, whether the locomotive isfacing in one direction or the other, whether the locomotive is precededor followed by cars on the same track, and whether the other tracks areoccupied by other cars. The structure of such receiving'apparatus may beany one of several forms wellknown to the art and may be of the typedisclosed in Letters Patent of the United States No. 2,102,435, grantedDecember 14, 1937, to W. P. Place for Receiving apparatus forcommunication systems. Such receiving apparatus forms no part of myinvention, but it may be helpful in the understanding of apparatusembodying my invention to explain that such receiving apparatus .isnormally conditioned for reception and is responsive to a carriersignaling current equivalent to a preselected carrier modulated by apreselected voice frequency for governing a cab indicator and is.automatically conditioned for reception of a carrier telephone currentwhen the signaling current is discontinued, the voice frequencies ofsuch telephone ting circuits electrically,

curr n tems: reprhdueed' at a"loud-'-speaker-'or telephone receiveiz i vI played ir'idi'cates that I the transmitting circu' is energized withsignaling current and that the system is in awork'ing condition. Thez-zab indithat the Signal' g current is discontinued due either-to -a'failureof the system or that remoteo'flice station is about to initiatetele"-" cator when extinguished indicates the operator at the phonecommunication. It is clear that suchcab Y consist ytiieumoauratcn areshifted so that a The 'cab 'indicater when: sis; j

indicator may be controlled through decoding apparatus of the Well-knownform and made'to display a 1 distinctive. signal for each of severaldifi'er'entcodes of the signaling current, andsuch cab signa1 whencontrolle'd'bycoded signaling current may be used to govern the speedand movement of therloco'motive on which the apparall rfangement'isleflected; v 7 Ihelmicrophone 's'lconne'ctedto the modulav and"to'efiectimodulation terssu ppli'd fro up he oscillator OSI by'thevolce irequencic produced bywspeaking into "the microph'one. whenthemodulator-is set for i tsubalnnced condition, thevside bands resultingquel lby are: supplied t BPF wiresl 5t and =16; thet'carrier'bein'gsuppressed by the balanced arrangement of the nicdulat'orr 'l'he CfilterBPF is proportioned and actuated as suppress one side b andand' pass the'l o furtherassis't inunderstanding the invention, :1 shall "assume thatthe-lower side band? is suppressed 'an'd: the upper side band is paratus"is mounted. It is to be seen therefore that communication may beeffected between v the operator at thecentral. oifice vCF and the crewof 'a locomotivedper'ating on'anyltrack of either yard RY 'or'OYwhencommunication current issupplied'to either one or both'of the twotransmitting circuits, it being understood, of

- course, that receiving'apparatus. of the form described above is:mountedon' eachsuch locomo tive. w

1 In order to better'sep'arate the two transmitinsulated rail "joints 6maybe helpful :whenplaced in theihump track in the vicinity of theoffice station CF, but such insulated rail'joints may not be required.

The transmitting apparatus is shown at the upperportion of the'drawingand this transmita ting apparatus would preferably be located at thecentral office CF and comprises as essential elements, ancscillator OSI,a microphone M, a'modulator MO, a band pass filter BPF, a poweramplifier PA, and a code transmitter CT together with an output circuitand threedifierent Q pper side: band "of; by 'filter BPFto th amplifierupanc l coridenser 1 1 manual operable switching means to be laterdescribed. v

The oscillator "0ST," modulator MO, filtenBPli and power amplifier PAare shown conventionally in order specific structure'of each ofthesedevicesfforms no part of i I may be any one of several'well-known'types.Furthermore these devices'will beexpl'ained only as required for a fullunderstanding of my -inven-' tion. I E I The oscillator OSI ispreferably "of electron tube type and generates a carrier current of apreselected frequency, the frequency of'the carrier current beingdetermined in 'part by a condenser 1.. The arrangement is such that whena relay DR to be referred "to later, is released to close back contact 8and condenser! is connected to theoscillaton a carrier current of afrequency of say, i v generated, andwhen relay DRI is picked upandcondenser l disconnected from the oscillator, the carrier frequency'is'shifted by an amount equal to a preselected frequency of say 1000cycles so e that the carrier current then generated is of the frequencyof 7000 cycles. The carrier current generated by oscillator OSI isdelivered to the modulator MO over wires 9 and It]. The modulator MO 7is preferably of the balanced electron tube type, the connections ofwhich are governed by relay DBL When relay DRl is released, 0105- ingits back contact 'I I ,a connection is completed by which a balancedpush-pull arrangementis ef-,

, fected for the modulator and when relay DH! is picked up to closefronthontact M, the connecto simplify the drawing since the forexamp1e',-6000-c ycles per second is my present invention andsuchdevices ",The' output side of filter BPF is I con- Ver wires l'l and I8to theinpu't' ter passed; necte min 15 f'ithe power amp'liiier PA. "Whenthe can-i urrent' of- 600 0' cyc1esper second is used a assumedyhereinbefor'e, and a voice frequency e 01 Oli t0-2500 cycles is considered,the the' telphone current passed en Trelay so that the; carrier "current'is of v .7000 rid the modulator lvlb is 'shiftedzto a parallel}rrangement then this, carrier current 'rier 5c renames-med bylthe voicefrequency or ioooycynesp- 'This carrier current ofnflOOO u sts use'c las a 'signaling currcnt. a

Thelam'plifier PA'fsmreferably ofthe electron tubet e andwheneithertheftelephone current ofthe r ang-e of 6500 8500 cycles or thesignalcmrenitj cf UQO cycles is applied-to its input terminals such"current is amplified to a *rela tively hig energy leveland'supphed toan output r t Theoutput circuit includes -a secondary f an outpu'ttransformer 20 whose Relay om controlled cui biased ":typeipush buttonPBand'the relay DR? trp'getl'ierv withffiu'sh buttonfPB f orm' a first'manu allly operable switching 'meansfor conditioning the itrains'r r-iittir-ig apparatus to supply either the carrier sigmimgmmm or' thecarrier telephone current. It followsthat the normal 'or' firstpositio'n o-f' thfe first "switohing'ineans conditions'thetransmittingapparlatus Itd'fsuppl'y the carrier signaling current tothefsecondary'wi'nding 1 Sci the outp fticircuitand the reverse or"second position I of thisfirst switching 'm'eans conditions "theairparatus'? to supply'the carrier telephone current totheseconiiarywinding H! of the output circuit.

Additional for this first switching meansiwill appear he'reinafter.v

I l-1e output circuit" connected to secondary o, windingl o'ftransformer is provided'with several fdifie'rent circuit paths five ofwhich paths are governed by a second' "manually operable switchingineains', here shown as consisting or four: separate "circuit Icontrollers P1, P2; P3 and P4. Each suit contr oller" of the second"switch i-r ig means mar in A 4 v Seated in the" drawing by solid l vsecond orreverse position illustrated lei "dotted lines in the drawing."

Q i A code transmitter orcoder CT'is provided is "of'ith'eran e of ipass'edz bs 'th'e filter BPF 'since- "the carrie'r current of 1000cycles is the equivahe upper side band' 'of the 6000:0ycle dar ofliiirigirzzrii's connectedit t output I w h over an obvious cir-"t-includi'ng (a normally'closed contact 22 of 'a operable to' ei tlier anorand as here shOWn it is of the relay type having three contactmembers I80, I20 and I which are operated as long as an operatingwinding 23 of the coder is supplied'with energizing current. Winding 23is provided with a circuit which can be traced from terminal B of aconvenient source of current, such as a battery, not shown, frontcontact 24 of relay DRI, winding 23, a normal closed contact 25 ofcircuit controller P4 and to terminal C of the same source of current.Hence when the first switching means is set at its first position withrelay DRI picked up and controller P4 of the second switching means isset at its normal position, coder CT is active to operate its contactmembers, the arrangement being such that contact member I80 is operatedto engage a contact 26 at the code rate of 180 times per minute, contactI 20 is operated to engage a contact 21 at the code rate of 120 timesper minute and contact member I5 is operated to engage a contact 28 atthe code rate of 75 times per minute. Each of the contact members I80,I20 and I5 is interposed in one of three paths of the output circuitand. which three paths are also controlled by controllers PI, P2 and P3of the second switching means.

The circuit controllers of the second switching means are also used togovern a fixed signal HS located along the hump track HT for indicatingto a locomotive pushing cars over the hump the speed and movementdesired. This signal HS may be of any standard type of fixed signal andas here shown is a color light signal capable of displaying any one offour different indications; namely, a green light to indicate proceed atnormal hump speed, a yellow light to indicate proceed at slow humpspeed, a steady red light to indicate stop and a flashing red light toindicate back up, The control efi'ected by the second switching meansover the three circuit paths of the output circuit which includescontact members of code transmitter CT and over the indication of thefixed signal HS is such that a distinctive code for the carriersignaling current is effected for each signal indication with the resultthat a cab indicator of receiving apparatus mounted on the locomotivewould be made to provide a distinctive cab signal for each indication ofthe fixed wayside signal, and as here contemplated the 180 code for thecarrier signaling current controls a cab signal which corresponds to thegreen light of the fixed signal to indicate proceed at normal humpspeed, the 120 code for the carrier signaling current controls a cabsignal which corresponds to the yellow light of the fixed signal toindicate proceed at slow hump speed, the '75 code controls a cab signalwhich corresponds to the flashing red light of the fixed signal toindicate back up and non-coded signaling current controls a cab signalwhich corresponds to the steady red light of the fixed signal toindicate stop.

The output circuit is provided with additional circuit paths whichby-pass the output circuit around the code transmitter and. the secondswitching means and each of these additional circuit paths includes asecond position contact of the first switching means, so that when thetransmitting apparatus is conditioned for supplying telephone currentthe output circuit is completed for by-passing the telephone currentaround the code transmitter and the second switching means. Suchadditional circuit paths will be described when the operation of theapparatus is described.

, The connections of the output circuit to the transmitting circuits arefurther governed by a third manually operable switching means comprisingtwo circuit controllers CI and C2.

It is believed that the manner whereby the three different switchingmeans govern the transmitting apparatus and the connections of theoutput circuit to the transmitting circuits can best be understood by adescription of the apparatus. In describing the operation of theapparatus, I shall first assume that a locomotive provided with properreceiving apparatus is pushing cars over the hump and hence occupies thehump track HT to the left of the central oifice station CF. Since thepush button PB is biased to its released position, the first switchingmeans occupies its normal position so that relay DRI is picked up tocondition the transmitting apparatus to deliver carrier signalingcurrent. The circuit controller P4 of the second switching means isplaced by the operator at its normal position and the coder CT isactive. In the event the operator desires the locomotive to proceed atnormal hump speed, circuit controllers P2 and P3 of the second switchingmeans are set at their normal positions and circuit controller PI is setat its reverse position. The operator would also set each circuitcontroller CI and C2 of the third switching means at its right-handposition as illustrated by the solid lines in the drawing.

With circuit controller PI reversed, a simple circuit easily traced iscompleted for a lamp 29 of signal HS and that lamp is illuminated todisplay a green light. A first circuit path of the output circuit isalso completed at the reverse position of contact 32 of circuitcontroller PI so that carrier signaling current coded at the 180 coderate flows from the top terminal of secondary winding I9 over frontcontact 3I of relay DRI, contact I26 of coder CT, reverse position ofcontact 32 of controller PI, wire 33, contact 34 of controller CI, wire35, line wire LI of the first transmitting circuit to point A, back thetrack rails of the tracks of the inbound yard and the track rails of thehump track HT, wire 36, contact 31, of controller CI and wire 38 to thelower terminal of secondary winding I9. Since this signaling current iscoded at the code rate, the cab indicator of the locomotive occupyingthe hump track HT or any of the yard tracks leading to the hump trackwill be conditioned to display a corresponding indication whichindication conveys the information to the locomotive crew to proceed atnormal hump speed. This cab signal indication is continuously displayedand would also serve to indicate to the locomotive crew an operativecondition of the communication system.

In the event the operator at the central oflice desires the locomotiveto proceed at slow hump speed, the first and third switching means areleft as above described but controllers PI, P3 and P4 of the secondswitching means are set at their respective normal positions andcontroller P2 is reversed. A yellow lamp 39 of fixed signal HS is nowprovided with a circuit including the normal position of contact 30 ofcontroller PI and reverse position of contact 40 of controller P2, andlamp 39'is illuminated to cause the signal HS to display a yellow light.With the controller P2 reversed a second circuit path of the outputcircuit, and which circuit path includes contact member I20 of thecoder, is closed and made effective so that carrier signaling currentflows from the top terminal of secondary winding I9,

It is to be seen, therefore, that I have provided simple and inexpensivetransmitting apparatus for train communication systems incorporatingnovel means for supplying carrier signaling current coded at diiferentcode rates or noncoded and for supplying carrier telephone current andwhich currents can be supplied to one or all of a plurality of differenttransmitting circuits associated with different stretches of railwaytrack.

Although I have herein shown and described only one form of transmittingapparatus for train communication systems embodying my invention, it isunderstood that various changes and modifications may be made thereinwithin the scope of the appended claims without departing from thespirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In apparatus for a train communication system, the combinationcomprising, transmitting apparatus capable of producing a carriertelephone current or a signaling current equivalent to said carriermodulated by a given voice frequency, a first manually operableswitching means having a first position to condition the transmittingapparatus to produce said carrier signaling current and a secondposition to condition the transmitting apparatus to produce saidtelephone current, an output circuit coupled to the transmittingapparatus to receive such currents and provided with three differentcircuit paths, a code transmitter having a contact member included in afirst one of said circuit paths, a second manually operable switchingmeans having a first position for closing said first one of said circuitpaths and a second position for closing a second one of said circuitpaths, a second position contact of said first switching means forclosing the third one of said circuit paths, and a transmitting circuitextending along a stretch of track and connected to said output circuit.

2. In combination with transmitting apparatus capable of supplying acarrier telephone current or a signaling current equivalent to saidcarrier modulated by a preselected voice frequency, an output circuit toreceive such currents from the transmitting apparatus and provided witha plurality of different circuit paths, a code transmitter having acontact member operated at a predetermined code rate and interposed in aselected first one of said circuit paths, a first manually operableswitching means having a first position to condition the transmittinapparatus to supply said signaling current and a second position tocondition the transmitting apparatus to supply said telephone currentand to close a second selected one of said circuit paths, a secondmanually operable switching means having a first position to close saidfirst one of the circuit paths and a second position to close a selectedthird one of the circuit paths, two transmitting circuits one extendingalon a first stretch of track and the other extending along a secondstretch of track, and a third manuall operable switching means havingdifferent positions for connecting said output circuit to either one orboth of the transmitting circuits.

3. In apparatus for a train communication system, the combinationcomprising, transmitting apparatus capable of producin a carriertelephone current or a signaling current equivalent to said carriermodulated by a given voice fre- 'quency, a first manually operableswitching means having a first position to condition the transmittingapparatus to produce said carrier signaling current anda second positionto condition the transmitting apparatus to produce said telephonecurrent, an output circuit coupled to the transmitting apparatus toreceive such currents and provided with three different "circuit paths,a code transmitter effective when energized to operate a contact memberat a preselected code rate and which contact member is included in afirst one of the circuit paths of the output circuit, a second manuallyoperable switching means having a first and a second 'position forclosing said first path and a second path of the output circuitrespectively, a second position contact of said first switching meansfor closing the third path of the output circuit, means including afirst position contact of the first switching means and a contact of thesecond switching means to energize said code transmitter, a transmittingcircuit extending along a stretch of track, and other switching means toconnect at times the output circuit to said transmitting circuit.

4. In apparatus for a train communication system the combinationcomprising, transmitting apparatus capable of producing a carriertelephone current or a signaling current equivalent to said carriermodulated by a given voice fre- -quency, a first manually operableswitching means having a first position to condition the transmittingapparatus to produce said carrier signaling current and a secondposition to condition the transmitting apparatus to produce saidtelephone current, an output circuit coupled to the transmittingapparatus to receive such currents, a code transmitter having a firstand a second contact member and which members are operated at difierentcode rates; a second manually operable switching means having a firstposition to close said output circuit through said first contact member,a second position to close the output circuit through said secondcontact member and a third position to by-pass the output circuit aroundsaid contact members; means including a second position contact of saidfirst switching means to by-pass the output circuit around said secondswitching means, and a transmitting circuit effective to transmit suchcurrents and extending along a stretch of track and connected to saidoutput circuit.

5. In apparatus for a train communication system, the combinationcomprising, transmitting apparatus capable of producing a carriertelephone current or a signaling current equivalent to said carriermodulated by a given voice frequency, a first manually operableswitching means having a first position to condition the transmittingapparatus to produce said carrier signaling current and a secondposition to condition the transmitting apparatus to produce saidtelephone current, a code transmitter having three difierent contactmembers which are operated at different code rates, a transmittingcircuit effective to transmit such currents and extending along astretch of track, an output circuit to connect said transmittinapparatus to said transmitting circuit, a fixed signal to govern trafficmoving over said stretch of track and capable of displaying fourdifferent indications; a second manually operable switching means havingfour different positions and provided with contacts closed at a firstposition to. interpose a first one of said code contact members. in theoutput circuit and to close a first position circuit of said fixedsignal, other contacts closed at a around the said second switchingmeans, and still another switching means-having different posisecondposition to interpose a second one of said members in the output circuitand to close a third position circuit of the fixed signal, and

other contacts closed at a fourth position to bypass the output circuitaround said code contact members and'to close a fourth position circuitof the fixed signal; and means includin a second position contact ofsaid first switching means to by-pass the output circuit around saidsecond switching means.

6. In apparatus for a train communication system, the combinationcomprising, transmitting apparatus capable of producing a carriertelephone current or a signaling current equivalent to'said carriermodulated by a givenvoice frequency, a first manually operable switchingmeans having a first position to condition the transmitting apparatus toproduce said carrier signaling current and a second position tocondition the transmitting apparatus to produce saidv telephone current,a code transmitter having at least two different contact members each ofwhich is operated at a code rate distinctive for that contact member, atransmitting circuit effective to transmit said telephone and signalingcurrent and extending along astretch of track, a fixed signal to governtraffic along said stretch of track and capable of displaying at leasttwo different indications, an output circuit to connect saidtransmitting apparatus to said transmitting circuit and provided with atleast three different paths a first and a second ofv which paths eachincludes a distinctive one of said contact members; a second switchingmeans operable to three 1 different positions and provided'with contactsclosed at a first position to close the first path of tions forselectively controlling the connections of the output circuit to saidtransmitting circuits.

8. In apparatus for a train communication system for a classificationyard the combination comprising, transmittingapparatus located at acentral ofiice and capable of producing a carrier telephone current or acarrier signaling cur-' rent, a first switching .meansat said centraloffice and having a first position to condition the transmittingapparatus to produce said signaling current and a second position toproduce said telephone current, an output circuit coupled to thetransmitting apparatus to receive such currents, a code transmitterhaving a plurality of different contact members operated at differentcode rates,

a fixed signal located along a track of the yard to govern theclassification of cars andcapable of displaying a plurlity ofdistinctivesignal indictions, a plurality of operating circuits for said signal toeffect said signal indications, a second switching means located at saidofiice and having a plurality of different positions each of whichpositions is effective to interpose a selected one of said contactmembers in said output circuit and toclose a selectedone of saidoperating circuits for said fixed signal, means including asecondposition contact of said first switching means to by-pass theoutputcircuit around said second switching means, a transmitting circuiteffective to transmit said signaling and telephone ourrents'and extendngat least along the track associated with said fixed signal, and anotherswitching means at said office and effective at times to connect saidoutput circuit to said transmitting the output circuit and to close afirst operating circuit for said fixed signal, other contacts closed ata second position to close the second path of the output circuit and asecond operating circuit for said fixed signal and other contacts closedat a third position to closethe third path of said output circuit; andmeans including a second position contact of the first switching meansto bypass the output circuit around said second switching means.

'7. In apparatus for a railway train communication system thecombination comprising, transmitting apparatus capable of producing acarrier telephone current or a carrier signaling current, a firstswitching means having a first position to condition the transmittingapparatus to produce said signaling current and a second position tocondition the transmitting apparatus to produce said telephone current,a first and a second transmitting circuit extending along two circuit.

v 9. In apparatus'for a train communication system for a classificationyard the combination comprising, transmitting apparatus located at acentral ofiice and capable of producing a carrier telephone current or acarrier signaling current, a first switching means at said centraloffice and having a first position tolcondition the transl mittingapparatus to produce said signaling current and a second position toproduce said telephone current, an output circuit coupled to thetransmitting apparatus to receive such currents, a code'transmitterhaving a pluralityof different contact members operated at differentcode rates, a fixed signal located along a track of the. yard togovernthe classification of cars and capable of displaying a pluralityof distinctive signal indications, a plurality of operating circuits forsaid signal to effect said signal indications, a second a switchingmeans located at said office and having different stretches of track andeach effective to transmit said signaling and telephone currents, a codetransmitter having a contact member operated at a preselected code rate,an output circuit for connecting the transmitting apparatus to saidtransmitting circuits, a second switching means having differentpositions effective at one position to interpose said contact member inthe output circuit and at another position to by-pass said outputcircuit around said contact member, means effective at saidfirst'position of said first switching means to by-pass the outputcircuit a plurality of different positions-each of which positions iseffective to interpose a selectedone of said contact members in saidoutput circuit and to close a selected one of said operating circuits.for said fixed signal, means including a second position contact ofsaid first switching means to by-pass the output circuit around saidsecond switching means, a'first transmitting circuit extending along thetrack associated with said fixed signal and a first selected portion ofsaid yard, a second transmitting circuit extending along a secondselected portion of said yard, each of said transmitting circuitseffective to transmit, said signaling and'telephone currents, and athird switching means at said office and having different positions toconnect said output circuit to either one or both of said transmittingcircuits. I PHILIP P. ASH.

